Two enemies who are sexually involved with each other, but are not allowed to have feelings involved, as this makes the whole system crash. Enemies by day, sexual enemies by night. They are not allowed to tell anyone either, or go on dates. They do it all indoors and it has to be done by night or in a dark place where they won't be found.
John and Mary hate each other, but they're actually having wild, crazy sex behind closed doors. Its called Enemies With Benefits.